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  1. #1
    Join Date
    Nov 2009
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    Halifax, Nova Scotia, Canada
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    Default Moisture content of wood and building boxes

    I've just got a bunch of wood from a mill to build about 40 boxes, and I'm wondering about drying - and how that will affect my measurements.

    Wood shrinks as it dries, so I've heard that's where the 9 5/8" deep dimension came from - manufacturers building boxes out of not-so-dry wood and allowing for shrinking as it dries - the box stays safely withing bee space requirements. 9 5/8 is about an 8th too big for proper bee space.

    So do I need to reach a specific dryness before making final cuts and assembling? Or is it safe to take wetish wood and build to 9 5/8 dimensions?

    Thanks,

    Adam

  2. #2
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    Sep 2010
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    Pacifica California, San Mateo County
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    Default Re: Moisture content of wood and building boxes

    Well, I don't think that you have to care much about wood movement so much. If all the the wood has the
    same/similar moisture content you should be fine.
    My only concern would be if the wood is very wet, gluing could cause some trouble. Really wet surface just don't glue
    very well.

    Cheers
    Stefan

  3. #3
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    Default Re: Moisture content of wood and building boxes

    Is the wood kiln dried, air dried, or green?

  4. #4
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by Michael Palmer View Post
    Is the wood kiln dried, air dried, or green?
    I believe the wood has been aired dried for some time. I doubt the mill would mill and sell green wood, but I guess it's possible. The wood is dressed, but there are a few boards where you can see it was the end of the log, and those ends are well-weathered and grey from what appears to be a considerable time outside.

    I don't have a moisture meter, but I suppose I can do the "weigh-sample-dry-it-in-the-oven-and re-weigh" approach to finding out what it's moisture content is, and then go to the percentages Cleo suggests...

    Adam

  5. #5
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by Adam Foster Collins View Post
    I believe the wood has been aired dried for some time. I doubt the mill would mill and sell green wood,
    I would doubt it too Adam. Cut off a 6 inch piece, measure across the width put it in an oven @250 for a couple of hours, measure again. See how much it shrinks. Keep in mind it would be easier to plane off 1/8 inch than to scab on 1/8 inch.
    Brian Cardinal
    Zone 5a, Practicing non-intervention beekeeping

  6. #6
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    Default Re: Moisture content of wood and building boxes

    Ask the folks at the mill how dry it is...they may have a tester. Ask their advice.

    One problem, if you allow the wood to dry too much, is cupping. I would say if the boards are cupped, the wood is very dry.

  7. #7
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    Park City Ky
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    Default Re: Moisture content of wood and building boxes

    Adam Foster Collins.... I use pine, cypress, and poplar rough saw from saw mills. My experience is that a 10 1/2 inch board will shrink between 1/2 and 3/4 inch over a period of one year If you have green, rough cut, or as you put it, wetish wood, and you cut it to 9 5/8 you would be looking at a finshed board, after shrink, of about 9 inches. I would say unacceptable.

    I try for 12 - 18 % moisture. This normally takes 9 months to 1 year, stripped, and air dried.

    There is another good thread on this same topic in Equipment and Hardware review.

    cchoganjr

  8. #8
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by Adam Foster Collins View Post
    Or is it safe to take wetish wood and build to 9 5/8 dimensions?

    Thanks,

    Adam
    I would say not. It is not only dimensional change you are concerned about it is warp and twist. Let it dry, air dry if you have to and then cut it up. Are you going to do any joining or planing?
    Brian Cardinal
    Zone 5a, Practicing non-intervention beekeeping

  9. #9
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    May 2012
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    McDonough, NY United States
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    Default Re: Moisture content of wood and building boxes

    I built 10's of boxes this year out of hemlock that was only cut for several days. I used rebate joints instead of box/finger joints so that shrinking didn't matter. I had no trouble at all. I made sure that I had planed, cut, built and painted within 3 days though - in hopes the layers of paint would slow down the drying of the wood and keep it more stable. It worked great. No issues at all. I did not measure my boxes after a few months but they may be a bit more shallow. I know frame clearance between boxes is tight on some of them. Maybe add an extra 1/8 or 1/4 to your depth just in case. It won't be enough to matter if they don't shrink.

  10. #10
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    Default Re: Moisture content of wood and building boxes

    stack the wood out of the rain and and air dry it for at least 9 months.
    Old Guy in Alabama

  11. #11
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    Toronto, ON Canada
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    Default Re: Moisture content of wood and building boxes

    Looks like this calculator might be useful for estimating shrinkage?

    It would appear if you're cutting dried lumber the change in size would be fairly minimal.

    I'm thinking of going with about 10mm between boxes on my dried cedar. At it's driest in my area I'm figuring it's doubtful it will drop below 6mm between boxes. I'm pretty sure the bees can still move through a 6mm space.
    Last edited by Beekeeping.IsGood.ca; 01-06-2013 at 06:21 PM. Reason: used a negative when I didn't mean to.

  12. #12
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by Beekeeping.IsGood.ca View Post
    Looks like this calculator might be useful for estimating shrinkage?
    Excellent link. Just what the OP needed.
    Brian Cardinal
    Zone 5a, Practicing non-intervention beekeeping

  13. #13
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    Default Re: Moisture content of wood and building boxes

    Buy 2 inch rough cut lumber direct from a mill and plane it down to 3/4". You get the better cut, and can select the grain more when you go to plane. Buy it oversize in width and edge it yourself to get an even better board.

  14. #14
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by jdmidwest View Post
    Buy 2 inch rough cut lumber direct from a mill and plane it down to 3/4".
    This approach turns 60% of the wood that you just paid good money for into worthless planer shavings! A better alternative might be to find a mill that knows how to cut the product you want to buy.
    Graham
    --- Practical reality trumps philosophy!

  15. #15
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by Rader Sidetrack View Post
    This approach turns 60% of the wood that you just paid good money for into worthless planer shavings! A better alternative might be to find a mill that knows how to cut the product you want to buy.
    Note I stated "rough cut" I would still have to plane since is approx 1 1/2" give or take. And the shavings go into the horse stall. But the rough cut is cheaper than dressed and finished lumber and is worth it if you own a planer. Sometimes 1" stock is too close to the 3/4" finished size to do much planing on.

  16. #16
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    Default Re: Moisture content of wood and building boxes

    Quote Originally Posted by jdmidwest View Post
    Buy 2 inch rough cut lumber direct from a mill and plane it down to 3/4".
    Rader Sidetrack is right. If you need 3/4" boards you can start with 1" rough stock. Generally anyone that saws lumber will saw a variety of thicknesses and will be able to provide 1" boards.
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    Ralph

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